Hi! We are Seth Wynes and Kimberly Nicholas, authors of a recent scientific study that found the four most important choices individuals in industrialized countries can make for the climate are not being talked about by governments and science textbooks. We are joined by Kate Baggaley, a science journalist who wrote about in this story

Individual decisions have a huge influence on the amount of greenhouse gas released into the atmosphere, and thus the pace of climate change. Our research of global sustainability in Canada and Sweden, compares how effective 31 lifestyle choices are at reducing emission of carbon dioxide, methane, and other greenhouse gases. The decisions include everything from recycling and dry-hanging clothes, to changing to a plant-based diet and having one fewer child.

The findings show that many of the most commonly adopted strategies are far less effective than the ones we don't ordinarily hear about. Namely, having one fewer child, which would result in an average of 58.6 metric tons of CO2-equivalent (tCO2e) emission reductions for developed countries per year. The next most effective items on the list are living car-free (2.4 tCO2e per year), avoiding air travel (1.6 tCO2e per year) and eating a plant-based diet (0.8 tCO2e per year). Commonly mentioned actions like recycling are much less effective (0.2 tCO2e per year). Given these findings, we say that education should focus on high-impact changes that have a greater potential to reduce emissions, rather than low-impact actions that are the current focus of high school science textbooks and government recommendations.

The research is meant to guide those who want to curb their contribution to the amount of greenhouse gas in the atmosphere, rather than to instruct individuals on the personal decisions they make.

And here is a write-up on the research, including comments from researcher Seth
Wynes: NBC News MACH

Guests:

Seth Wynes, Graduate Student of Geography at the University of British Columbia in Vancouver, currently pursuing a Doctor of Philosophy Degree. He can take questions on the study motivation, design and findings as well as climate change education.

Kim Nicholas, Associate Professor of Sustainability Science at the Lund University Centre for Sustainability Studies (LUCSUS) in Lund, Sweden. She can take questions on the study's sustainability and social or ethical implications.

Kate Baggaley, Master's Degree in Science, Health, and Environmental Reporting from New York University and a Bachelor's Degree in Biology from Vassar College. She can take questions on media and public response to climate and environmental research.

I have a question about the paper vs plastic debate. I am a chemical engineer, and I have done research on some of these type of debates when I was in college. Most studies found that paper actually takes more energy to make, and recycling wood pulp actually creates a higher CO2 output on the environment, while most plastic items are relatively simple and easy to make, without the massive expulsion of CO2 on the environment. While this is true, it is also true that plastics,when littered in the environment do have a strong impact on wildlife. My question is, how can paper recycling create more CO2 output but still be considered a safe replacement for plastic?

In our research, we found that grocery bags were often a focus for recommended climate actions by government documents and science textbooks. For example, one of the high school science textbooks we analyzed says “making a difference doesn’t have to be difficult” and provided the example of switching from plastic to reusable shopping bags to save 5kg of CO2 per year. However, our study found that this is less than 1% as
effective for saving greenhouse gas emissions as a year without eating meat. While reducing plastic waste that ends up in the oceans is an important environmental issue, our study shows that individual choices to eat a plant-based diet, avoid flying, live car-free, and plan smaller families make a much bigger difference for the climate.

I was shocked at the amount of plastic bags used at Walmart or similar stores when I moved to the US from Germany. Many supermarkets/grocery stores in Germany don’t offer plastic bags at all but instead offer reusable bags so the customer has to either carry everything in their arms or buy a reusable bag. I think it’s up to the major supermarkets or grocery stores to collectively change their habits in order to see a significant change in pollution from plastic bags, but that is highly unlikely.

This is as important culturally as it is numerically. If we see plastics as disposable, we continue to cycle them quickly through our resource streams and litter the environment with them. The effect on wildlife and landfills is long-term and systemic, in turn affecting plant life and atmosphere.

Paper, by comparison, creates more GHG and takes more energy to produce, but requires no oil (necessarily) and produces no durable waste. It's only helpful to consider GHG output if we also include other metrics as well.

One effective way to gauge the impact of waste is in the amount of time it takes to break down and reintegrate into the food chain. For paper, in a matter of days or weeks it will compost into available carbon (if composted -- not landfilled, where it makes more GHG). Plastic will take decades to centuries to reintegrate, if at all. Some plastics won't break down until yet-to-evolve microbes adapt to digest them -- and we don't know what they would excrete. Possibly toxins. It's not a good wager.

For this reason, it's best to (1) reduce dependence on so-called disposables, (2) reuse these items, despite the social stigma of being "cheap," and (3) choose recyclables that are low-impact (compostables, metal, and glass are best -- plastics degrade when recycled, release toxins, and have to be mixed with new plastics to be reformed into new goods).

Most of all, we need to put our needs before our wants -- balance before convenience. If there's something we should make more convenient, it's sustainable choices. This is the foundation of a stable and healthy living system.

Not in the case of plastic, because it's not sequestering carbon that would otherwise be in the atmosphere -- it's taking carbon stored in the ground. And once disposed of, it's just becoming piles of trash in landfills, which leech toxic PCBs and stuff into the groundwater. When combined with organic material (food waste and paper) in landfills, the plastics seal off oxygen and harbor anaerobic methane-excreting bacteria (methane is 20 times more greenhousing than CO2). Or worse, plastic ends up in oceans, where it piles up by the tons and fucks with wildlife. So all around, plastic is a big ol' detriment to living systems.

To clarify what I mean by breaking down: for the carbon in paper to "break down" on the ground and into the soil is a good thing, because it becomes available for plants, fungi, and microbes to build with (most of these organisms get part of their carbon from atmosphere and part from soil). On the other hand, for paper and other organic material to "break down" into methane or CO2 in the atmosphere is a bad thing, and this is what happens in landfills due an imbalance of oxygen, nitrogen, and carbon.

TL;DR: at the rate we produce and dispose of them, plastics are not fitting into the environment in a way that makes long-term sense. Organic materials like paper are better IF we dispose of them soundly. Composting organic material makes it into nutrients for living systems, while sending it to landfills means it will produce methane, which is about 20 times worse than CO2 for climate change.

Still TL;DR: we should minimize our use of landfills (and eventually move past this habit altogether) and compost whatever we don't consume. This means only using plastic for durable goods, and ceasing the "disposable" idea completely.

I'd say it's just as important to advocate for these options in places that don't have them if that's where you find yourself. I've been a big supporter of Phoenix, Arizona's barely-decade-old light rail line, which, while needing a lot of work, is expanding and paying off.

Yeoman's work for such things can be as simple as trying to convince people skeptical to at least consider it. Then we can move forward.

Living car free is simply not an option for most of the people in the US. It is really only an option to people who live in major metropolitan areas. Even then you can't get by without a car most of the cities in the US unless they have 24hr metro transportation which is limited to only the largest cities.

Limited travel and switch to hybrid or pure electric vehicles is going do more to curb emissions.

Yeah there's lots of places you need a car. But even then you can still choose to buy a small hatchback rather than a massive SUV or truck for personal transport.

As a non-American the desire to own a massive SUV seems very odd, I expect a lot of it is just down to fuel prices. It's simply not economical to run a vehicle like that where I live due to fuel price/taxes. That would be a simple way to get people to switch to smaller more efficient vehicles although I'm sure there would be plenty of backlash from people wanting to keep their massive cars.

Looking at greenhouse gas isn't the only environmental metric. The long term detrimental effect of plastic litter is a whole big issue of itself. It's better to read as "these things are great, and to make even more imapact then the listed are really helpful."

Hydrocarbons (coal, gas, oil) are locked up within the earth, until it is accessed, and not normally a part of the ecosystem, exception being some methane pockets; once used, it doesn't turn back into oil. Vegetation grows, dies, and decomposes or burns (both release CO2), and grows again, so there's balance. This is why growing trees is simply not enough, but it does help. Pants utilize carbon, but it's still being used, we need to find a way to remove it, or lock it up long term.

Yes, eating less beef is a very positive choice you can make for the environment! One study in particular answered your exact question: they found that the most effective thing you can do for your diet is to eliminate meat (35% reduction in emissions from food). But switching from intensive meats like beef to less intensive meats (like poultry) results in an 18% reduction.

Other studies have found similar results. A recent paper found that substituting beans for beef could achieve large enough reductions to cover about half of the US climate goal for 2020.

On average there is a benefit from moving from a vegetarian diet to a vegan diet. How you actually do this as an individual could change the results, but our findings suggest that switching from an omnivorous diet to a vegan diet saves about 900kg of Co2e each year, whereas switching to a vegetarian diet saves about 800kg.

For example if I want to switch to a vegan diet and no longer use dairy (and I live in "the dairy state" so you can assume there is very little transportation of dairy products), I would buy avocado or coconut products instead of butter and milk. Is the shipping of coconuts and avocados from tropical climates to the northern U.S. still better than using cow-based dairy?

Like all good questions, the answer is that it depends. I have read about this a lot, and my understanding is that vegan still comes out ahead. When dairy is produced, you have to grow and transport all the food to feed the cow, produce extra water for the cow, and then the cow releases methane. Once the milk is produced, you have to pasteurize it, refrigerate it and transport it all before it spoils. For a coconut or avocado, you still have to input the resources to grow it, but it is significantly less than feeding a cow, and many products like coconut milk do not need to be refrigerated and are less prone to spoiling.

Transportation is relatively small compared to the overall impact of raising an animal. This is why it can be more efficient (from an energy standpoint) to buy something from an industrial scale farm in South America than from a small local farm that is much less efficient.

‘We find that although food is transported long distances in general (1640 km delivery and 6760 km life-cycle supply chain on average) the GHG emissions associated with food are dominated by the production phase, contributing 83% of the average U.S. household’s 8.1 t CO2e/yr footprint for food consumption. Transportation as a whole represents only 11% of life-cycle GHG emissions, and final delivery from producer to retail contributes only 4%. Different food groups exhibit a large range in GHG-intensity; on average, red meat is around 150% more GHG-intensive than chicken or fish. Thus, we suggest that dietary shift can be a more effective means of lowering an average household’s food-related climate footprint than “buying local.”’

Eating local is not always more energy efficient because small farms tend to be much more inefficient than large-scale farms. Shorter transportation doesn't always close this gap.

If you bring in other factors such as water use or impact on the local economy, the equation shifts. Maybe your local farm uses more water, but you live in a naturally rainy area so it doesn't stress the watershed like it might in the Central Valley of California. But maybe the California farm gets some energy from solar panels and practices good composting practices. It all depends on what variables you look at and which ones you consider to be the most important.

A friend tried to answer this a bit ago. While the exact answer depends on many factors, this is a good starting point:

‘We find that although food is transported long distances in general (1640 km delivery and 6760 km life-cycle supply chain on average) the GHG emissions associated with food are dominated by the production phase, contributing 83% of the average U.S. household’s 8.1 t CO2e/yr footprint for food consumption. Transportation as a whole represents only 11% of life-cycle GHG emissions, and final delivery from producer to retail contributes only 4%. Different food groups exhibit a large range in GHG-intensity; on average, red meat is around 150% more GHG-intensive than chicken or fish. Thus, we suggest that dietary shift can be a more effective means of lowering an average household’s food-related climate footprint than “buying local.”’

I actually heard about cattle being the leading cause of GHG for the first time on Leonardo DiCaprio's Before the Flood. Like you, I started cutting out beef from my diet when I learned that. I always felt like I wasn't making much of a change by reducing beef in my diet, but I continued it because I'm a fan of Gandhi's "Be the change you want to see in the world."

Anyway, the reason I'm responding to you is because, as a healthcare professional, I wanted to point out the fact that there are very real health benefits to cutting red meat from your diet, which, to answer your question, does make it worthwhile.

I stopped watching What the Health about a quarter of the way through because it was unbearable. I'll give Food Choices a look, though.

I actually read a great article by Nat Geo on The Evolution of Diet and it had an interesting brief discussion on the role of meat in our evolution.

I'm probably never going to eliminate meat from my diet, and I find that to be an unrealistic goal to ask of the general public. But being more aware of the different types of meat and their effects on both health and the environment could help us in moderating the proportions in which we eat different types of meat (ideally, a low proportion of red meat and a high proportion of white meat, like fish and chicken), while increasing the proportion of non-meat foods we eat.

how accurate is it that individual choices, while great and all, are a drop in the bucket compared to what industry is doing? shouldn't "voting" and "boycotting/informed spending" be high on this list?

There is a close link between production (by companies) and consumption (by individuals), and both are important to consider for reducing greenhouse gas emissions.

Individuals definitely play a big role in the climate; more than 60% of global GHG emissions come from household consumption choices, primarily mobility, shelter, and food Ivanova et al., 2016.

It’s also true that the majority of greenhouse gases in the atmosphere have come from burning fossil fuels, and these can be traced to the companies that produced them, with 63% of cumulative emissions in the atmosphere traceable to 90 companies Heede 2014. There’s a nice visualization in the Guardian of these data.

Keeping fossil fuels in the ground is critical to meet the below 2° climate Meinshausen et al., 2009; McGlade and Ekins, 2015, and one important way to do this is by making sustainable lifestyle choices to reduce the demand for fossil fuels.

Political action can definitely be an important way for individuals to act collectively and make an important climate impact, but we weren’t able to quantify this impact (in tons of greenhouse gases saved), so we couldn’t include it in this study. The divestment movement is an important example of boycotting that is having a big impact.

Informed spending is another strategy, but previous studies have shown that the climate impact from the direct consumption of “stuff” (e.g., clothing, electronics, household goods etc.) tends to be smaller than transport, housing (electricity & heating), or food. Therefore, making informed spending choices on stuff is not as high-impact as focusing on avoiding flying, living car-free, or eating a plant-based diet.

For example, a US household study by Jones & Kammen, 2011 showed that transport was about 30% of household greenhouse gas emissions, housing (mostly electricity & heating) 27%, food 15%, and “stuff” only about 12% (see their Figure 1).

I assume all figures you provide in your answers are in relative terms.

I'm curious what kind of impact would an individual have in absolute terms. For example a train will leave the station even if it's empty. Similar for an airplane, it will take off regardless of being full or half-empty. These things are on the level that probably no realistic number of individual initiative will have an impact on and it's something that only governments or the companies themselves can change.

In light of these scenarios, how does my individual impact on CO2 emissions change?

Train and airline industries will match the number of flights to demand, so it does propagate, even if there's an interim time of half-empty flights, over time somebody finds a way to optimize routes to save the company money

Are people reading the research underpinning the basic claims in this AMA? I make no claims to having a PhD, but why is no one challenging one of the fundamental arguments presented here? The authors are positing that because the supply chains necessary to maintain a house/have a child/eat meat account for a majority of global GHG we should stop doing those things because that would have the greatest impact.

This is like noticing that your arm is infected and all the systems (vessels/blood/nerves) are negatively impacting you due to the infection so clearly the most effective solution is to cut off your arm.

It definitely would have a huge impact, in fact in the majority of cases if you do it early enough and in a proper way, you will remove the infection and any chance of it causing damage to the rest of the body. But, shockingly, and seemingly unnoticed, you will no longer have an arm.

In these specific scenarios relating to climate change you aren't even chopping off the arm! You're removing the finger and assuming that that will have an impact on the underlying structures. Yes, if everyone lops off a piece it will have a broader impact, but at that point why not go for the deeper fix anyways.

In this analogy, it makes much more sense to me to try and keep your arm and try to change the underlying mechanisms that are causing/connected to the infection.

We need to recognize systems we use are the primary polluters and that the answer is not to stop seeking the products/lifestyle/children we desire, but in fact to accomplish these passions in a way that is in balance with our environment. If you imagine that you as an individual on a small scale are somehow altering the trajectory of global warming by not driving, it seems like you have fallen for the faulty logic presented here.

You can look at the only country that has gone the one child path or simply lack of sustainable population to see the dangers to society. Obviously, if you already assume less humanity is a good/necessary thing or being down an arm isn't really a big deal, or global communities having access to efficient transport, or the elderly being able to get around aren't important it's a moot point.

Your argument is that we shouldn't stop doing these things, we should find technological improvements to reduce their impact on the environment instead. See this question and answer which discusses the feasibility of some such improvements.

Choosing to not have a child, or to have fewer children, is something I can do now to have an immediate, ongoing, and quite large impact. That is not at all analogous to cutting off my arm. Even waiting until you're older to have children would have some impact.

Nobody said we had to legislate (eg China). Individuals can make a personal responsible decision.

How does an extra person release 58t of CO2 per year if the other emissions are so low?

So if driving, flying and bad eating habbits only can account for 5t per year, what causes the rest +90% of the carbon foot print?

Also how is the living car free is calculated? Is it based on walking instead of driving? Riding bike instead? Using bus instead? Using train instead? Moving next to work place and walking instead? Also some people drive car 1km per day, others 200km per day.

This is a great question, but the answer isn't intuitive. To calculate the magnitude of this choice we relied on the research done by Murtaugh and Schlax. In their system, a parent considering the effects of having an additional child is responsible for emissions according to the fraction of their genes that they pass on (i.e. each parent is responsible for 1/2 of their children's emissions, 1/4 of their grandchildren's emissions and 1/8 of their great grandchildren's emissions, and so on for many generations). They used average birth rates and life expectancies to show how many children one new child is likely to have in a certain country (and how many offspring those children would have and so on). All the emissions from these descendants were divided over the life expectancy of each parent (80 for the case of a female in the United States). We think it's appropriate to include multiple generations for a choice that will have multiple generations worth of consequences, but this results in a much larger number than the per capita emissions of an individual.

In their system, a parent considering the effects of having an additional child is responsible for emissions according to the fraction of their genes that they pass on (i.e. each parent is responsible for 1/2 of their children's emissions, 1/4 of their grandchildren's emissions and 1/8 of their great grandchildren's emissions, and so on for many generations).

I understand why you choose to use someone else's research, but that method is exceptionally flawed when used in a comparative study like yours.

You would need to examine the question in an ecological framework. Population growth is limited by resource availability: it's a sigmoidal curve, not an exponential. This paper's model is exponential.

In economic terms, your not having a child decreases demand for the necessary items to raise a child, which means that price will decrease, which will mean someone else can afford a child. So using their number far, far, far overestimates the effect your having a child will have on total carbon.

Additionally, you would want to deploy a discount rate to future emission. Preventing carbon release now is more valuable than preventing it in the future.

This seems to be misleading way to estimate it. While you’re correct that the decision may have an impact for generations, you’re accounting for all of that now rather than when it will have the impact. Depending how many generations you do the math for, you could make this number as high as you wanted.

It also ignores that the decision point we’re interested in is now, at within the next ten years, and not 75 years from now, at which point we’ll either be already screwed or have figured out a way around this.

I guess on a gut level the number seems way off, and opens you up to criticism of your approach. I just had a kid, and there’s no way we’re consuming that much more CO2. We have a bit more food consumption and consumer spending, but we’ve also stopped traveling. She might consume that much once she leaves the home in 18 years or so, but she’ll be making her own choices in a very different world.

If each couple only had one child, and each child is responsible for the same amount of emissions over their life time then the sum of their emissions is 1+1/2+1/4+1/8+1/16+1/32+1/64...~= 2

With infinite generations of one child, your emissions can only double. With two children each generation it will increase by 1 each generation, but it may average out that the people who are less likely to have a kid outweigh the people who have two kids.

EDIT: You do have a good point though. It seems like a questionable way of calculating it. I don't know the science enough to judge it though.

You're right in that scenario. I was thinking more of a scenario where the rate is 4+ kids per couple. If I'm doing my math right, each successive generation accounts half its number to me, but doubles in size, so that gives essentially infinite CO2. Maybe that makes sense, since we obviously can't sustainably double each generation, but still odd.

Even in a simple replacement with 2 people having 2 kids, this method accounts 4 people's worth of CO2 within my lifetime. If you assume we had those kids at age 20, live to 80, and every subsequent generation is the same, the fourth generation will be born the year we died, so the actual CO2 in my life is 100% * 1 (me), 75% * 0.5 (my kids), 50% * 0.25 (grandkids), 25% * 1/8 (great-grandkids), and everything beyond that happens after I'm dead, total of 1.28. That means the 4 accounted to my lifetime is 2.72 larger than what would actually happen in my lifetime, and the rest is happening after the year 2077.

I'm not denying kids are expensive from the CO2 standpoint, but the math here seems like a big stretch in order to come up with the numbers they're quoting. It also minimizes the impact of not driving or flying, which people are more likely to change than they are their views on having children.

And what about when the two parents die after having one child? And that child grows up and marries another person to again only have one child and then they die. So the plan to reduce the human species carbon footprint is to simply cut our world population in half? This isn’t a fix it’s a bandaid.

We calculated the effect of living car free based on the average number of kilometers traveled by a vehicle in a region per year, as well as average vehicle occupancy. We include emissions from car production and maintenance in addition to combustion of fuel (we basically tried to include the full life cycle of the car). You're correct in noting that how you go about living car free will determine the effectiveness of that choice. The number we suggest assumes that you replace average use of a vehicle with a zero emissions alternative (biking or walking). Replacing your car with public transit will not be quite as effective, though you're likely to travel fewer kilometers and even if you don't you can still expect a 26-76% reduction in emissions.

if i teach my children to also live without cars and air travel, etc. wouldn't that not significantly affect this high number ? Also the effect that governments tend to act on large population declines by stimulating birth rates, wouldn't that change the game as well?

It's based on constant emissions. The authors of the paper also do the calculations for an optimistic scenario (where the planet drastically cuts emissions) and a pessimistic scenario. This does cause very different results, but no matter how you approach the calculation you end up with an answer where this is still the most important choice you can make regarding the climate.

For some environmental problems technological advances are an easier route. For instance, society has addressed the problem of the hole in the ozone layer using technology and without much help from the public.

The correct answer to your question is the solution must be economic. Economics always wins.
Trying to convince everyone to stop eating meat will never work, and anyone who thinks it will is deluded in the extreme. The correct solution is to perfect lab-grown meat. Why? Because it has the potential to:

It's a win-win-win, and once developed, would very quickly come to dominate the market. All of the effort being dumped into the hilariously futile effort to curb meat consumption should be directed towards developing lab-grown meat.

The air-travel industry is exactly the same. People aren't going to stop flying - end of story. If you actually want to beat Climate Change, you need to come up with a method that actually has a chance of succeeding. In this case, that would be coming up with a solution that either severely reduces or eliminates the carbon footprint of airplanes. That could be bio-fuels, it could be something else. But it must be a solution that airlines are incentivized to adopt.

I absolutely agree. I find it absurd that we have to resort to education and individual government initiatives to solve this pressing problem. If we care at all of the climate and world that our children grow up in, we need to press for a carbon emissions tax.

That would eliminate all the man-hours spent thinking about weighing the environmental impact of individual and corporate actions, and reduce it to a simple cost minimization and profit maximization problem.

Taxing meat and flight more would also help, and unlike the technological solutions it could be done tomorrow. It would also automatically direct more resources towards developing the technological solutions.

Not OP, but studying Forester. There are many things you can do to better the environment with your 6 acres. I feel like this thread is heavily focusing on the emission and air quality aspect of environmentalism, but there are many other aspects that you could directly affect as well.

Firstly, if you have any streams running through your land, especially if you are near ag land, you could put in an effective vegetative stream buffer. These buffers are beneficial for multiple things, the biggest being 1) They prevent erosion which reduces sediment loads from being carried into the stream and polluting the water quality. This makes the stream less habitable for aquatic species, leads to more work in water treatment when the stream inevitably connects to a larger water source, and overall is a huge issue that is often overlooked (plus even small scale can really make a difference!) 2) These buffers create habitat for wildlife as well as safe corridors for animals to travel. 3) Often times these buffers are also planned to include nut and Berry producing species that will also have a huge impact on wildlife health and diversity. 4) This is very important if you are near crop fields or anyplace that applies chemicals. Nitrogen is a HUGE water polluter and is a very big issue in many states especially Midwestern states bordering major rivers. The gulf of Mexico is damn near uninhabitable due to the hypoxic (low oxygen) waters. This is largely because of the heavy use of pesticides/herbicides and just general increase in nitrogen. These buffers can be designed to remove over 90% of the nitrogen that flows over from at fields. THE BEST PART IS, there are many options out there (crp programs for example) that will pay for almost the entire project and will pay you annually more than the going rate for land rent. (120% I think...). AND, at most it only requires about 50 feet on each side of the stream adding up to a relatively small amount of acres over the course of a few miles.

Another easy management practice that will greatly benefit wildlife is to leave the dead trees there. It may sound weird, but dead trees (although maybe slightly ugly to look at) are great for almost all woodland creatures! Standing or downed dead timber provides food, shelter, cover from prey, and will eventually decompose and improve soil qualities!

As someone mentioned, you could also plant shrubs and tree species that have wildlife benefits! Berry producing shrubs are great (there are some invasive that you should avoid. Although they may have berries they are very aggressive, take over and suffocate other plants, and actually have little to no nutritional value to birds and small animals). Flowers and other Forbes can also be great for insects and butterflies!

Remove invasive species! You could easily find these on a local page with helpful tips to identify and deal with them. These typically aren't great for providing food, and often become to dense to allow corridor and nesting.

A little more technical, but thinning (selectively removing trees/shrubs) can also be a great option depending on the circumstances. It can help the natural carbon cycle along, and provide a more natural forest density to benefit animals. Added benefits: Can potentially produce an income that can be put to other management plans, and can also make the place more aesthetically pleasing.

There are lots of small things that can be done. Even minor changes can greatly increase wildlife population and diversity if you are an animal lover! Call your local forester. Often times they are busy and can be spread thin due to a sheer lack of employment, but usually they would be more than happy to give you some more specific tips, check the place out, and maybe even help prepare a management plan!

Hopefully this helps! I'm on mobile right now, but I'd love to share more if anyone has any questions!

Since Michigan only gets 8% of its electricity from renewable energy, putting a large solar installation on the land would be one possible way. Unfortunately that's a rather expensive solution, especially since there are almost no tax incentives, rebates, or exemptions for residential solar installs.

I'm a climate scientist that unfortunately flies to conferences once a year to share my research. I don't think we're at a point yet where early career scientists can forego these opportunities without significantly hurting their careers. Thoughts on carbon offsets or other approaches to reducing carbon footprint of a climate scientist?

My current research is actually investigating how to reduce air travel emissions from public sector institutions. First let me say that we know this matters because statements about how much you fly affect your credibility regarding climate change. And yet, as you point out, some amount of flying seems necessary in this career. My coauthor, Kimberly Nicholas wrote a personal piece about this problem in Scientific American, but in short we have both tried to replace air travel by taking the train whenever possible. Our institutions can also help us to reduce air travel by providing high quality videoconferencing equipment; even when you account for the embodied emissions of this equipment you tend to come out ahead.

I haven't seen any studies on whether use of carbon offsets causes moral licensing and thereby increases the amount of flights that people take, though this might be the case. I do have unpublished results showing that faculty are somewhat skeptical of the effectiveness of offsets. I think where possible it's best to reduce our air travel and rely on offsets as a last resort, but that's just my opinion on the matter. Also, if you are flying in business or first class it makes a pretty big difference if you take up less space and downgrade your ticket to economy.

Thanks for asking this, I’m bummed you didn’t get an answer. I was also wondering how the developing world factors in to the conversation.

I particularly am curious about birth rates: seeing as having one fewer babies in your family has the greatest impact of all the items they listed, and that developed countries already have seen slowed, if not stagnating, birth rates, how do we reconcile that with the less developed countries? Certainly lower birth rates across the global board would be the ideal carbon reduction, but that’s not a topic that’s easy to broach nor necessarily feasible without disposing of the concept of countries altogether.

Perhaps it's in part the developed countries responsibility to help here. They've got the benefit from fossil fuels to develop their societies and now that they've used them to develop renewable technology perhaps they should just give it to developing nations for free. No patents or licensing fees etc.

The birth rate is harder since that is affected by culture, education levels and living standards. But they could start (and probably already do) offer health and sex education and provide free birth control so that people in developing countries can at least make better informed family planning choices and have the resources to implement them. Much easier said than done I know but maybe necessary in the long term.

One topic I find surprisingly absent is the time of day used for energy consumption.
Energy storage on a large scale is very expensive and inefficient, so companies will adjust their power output at peak times of day by burning coal, for example, a very high-emission fuel, while at low usage times, power is left unused.
Was this ever considered for this study? What options to change this would you suggest?

My utility has a "demand response" program for the summer. You give them the ability to throttle back your AC at times of peak demand, they give you a small bill credit. I didn't even notice them doing it.

Other utilities have time of day pricing. Texas has a particular surplus of wind power at night, some utilities offer plans with free power at night and higher rates during the day. I haven't seen any numbers on how popular these plans are or how they change behavior. I've heard about timers on major appliance being popular with these plans, as well as extra freezers that run at night and get opened during the day for cooling, a kind of storage. Electric water heaters with a tank can also function like storage.

I believe time of day and demand response programs for industrial customers are generally bigger than the ones for residential customers. That could change with greater use of renewables and electric cars.

It's really hard to guess at the magnitude of any action without knowing a lot of specifics. Ideally if the company is burning the wood anyway it would be great if that energy was used to generate electricity (as a biofuel). That energy could maybe be used on site by the company or put into the electrical grid so that fossil fuels wouldn't need to be burned in other areas to make that same electricity.

I remember seeing something about how switching to an electric vehicle may not be as environmental friendly as some may think because the electricity used to charge the vehicle is most likely still being produced by non-environmental friendly sources. Would you recommend switching to an electric car or even a hybrid? And how would that compare to going car-free?

In our study we found that electric cars still results in an average of 1.15tCO2e emitted per year, which means switching from a typical gasoline powered car (2.4tCO2e per year) would save about one tonne of emissions. But, the emissions of an electric car vary quite a bit depending on the emissions intensity of the electricity grid that's being used to charge them. So if you're in an area that uses a lot of coal, it's probably a good idea to pass on the electric vehicle for now. Generally speaking, electric cars are the most efficient, followed by hybrids, but living car free is the most effective way to reduce emissions in this category.

Then the emissions associated with an electric car would be very low. You would still have some emissions because producing the car wouldn't be carbon neutral, and even hydro and wind create some emissions (the steel used to produce the wind turbine probably wasn't made with 100% renewable energy). But in such a case an electric car would be much more efficient than a car powered by gasoline.

That's a good thing to consider, but as Seth pointed out electric vehicles are still a better option. Just on a per-unit-of-energy basis, electric motors are about 90% efficient where ICE's can't do much better than 30%. Also consider the fact that gasoline doesn't need to be transported around by another gasoline consuming vehicle (gas tanker to gas station) to power the electric car, the infrastructure (electrical grid) there is more or less static.

Can we do enough to save ourselves, or is it too little too late? I’ve made a number of changes as an individual: I recycle, vegan diet, reduced transport footprint, power sourced from solar panels, but feel like it doesn’t probably amount to anything when I consider the bigger picture. Do you honestly believe there’s enough time, and will, to make significant change?

Personally, I definitely relate to struggling with linking my own individual choices and limited sphere of influence to the scale of the climate challenge. Sometimes it feels overwhelming.

That’s one reason Seth and I did this research. We wanted to identify what individual choices really make a difference for the climate, so people who want to step forward can focus their limited time and energy effectively. We found the four consistently high-impact choices were to eat a plant-based diet, live car-free, avoid flying, and plan smaller families. It sounds like you’re well aware of this already and taking it into account in your personal decisions. I’ve also worked to put these choices in practice myself.

I think the next step after considering one’s own behavior is to look around at your community: your neighborhood, your workplace, community groups where you’re active. See where you can start conversations about making changes to amplify what you’re doing personally- for example, questioning a work culture that equates flight miles with status, or making delicious vegetarian meals the default at work or social gatherings.

There are also many ways for an individual to act collectively and working at larger scales, to be part of political, social, or economic campaigns that focus on the bigger picture. I think these can link with the many encouraging examples of things headed in the right direction- for example, Copenhagen has committed to be fossil-fuel free by 2030, and hundreds of US cities have committed to 100% renewable energy by 2035.

Sure. There are hundreds of studies into this since the late 90s, so I linked a review paper because it's normally more reliable than just picking 1 paper. But if you want specifics, you could check out this. It's based on a big European project from 2005, so bear in mind that technology has improved since then so current energy payback periods are better.

There are plenty of newer papers but I'm struggling to find something open access (I assume you don't have access to paid journals via a university or similar).

Thank you so much for doing this AskScience AMA. In your estimation, was 400 ppm of CO2 a genuine tipping point or was it just symbolic? I can understand the reluctance (for various reasons) to proclaim that anthropogenic climate change is irreversible; nevertheless, the truth is the truth. I'd appreciate your (collective and apolitical) viewpoints on this.

For me, it was certainly extremely worrisome to see that humanity had crossed the 400ppm CO2 threshold for the first time in the last 800,000 years. The Planetary Boundary (meant to “define a safe operating space for human societies to develop and thrive”) for CO2 is set at 350ppm (with an upper range to 450ppm). The further we exceed that limit, the more risky the impacts of climate change are.
EDIT: wording

What do you think needs to happen for these individual strategies to happen at scale? Do you think it's possible to develop legislation that would encourage new behaviors without treading into the "controlling your personal life" space? Thank you!

Seth and Kim might be able to chime in with more details, but: this research isn’t intended to guide national policies. When it comes to family size, it’s more about giving people one more thing they might consider. Teenagers might be more receptive to these strategies than adults, since most of them haven’t yet decided where they will want to live, how they want to commute, how many kids they will want to have, etc.

I hear that I need to not eat meat, stop driving etc... all the time. Then I hear that a fleet of 16 cargo ships pollute more than every single car on the road. Due to poor fuel selection and inefficiencies of shipping.

Why are we spending so much time and energy on small individual choice when the real change should be much easier to accomplish given low hanging fruit like 16 ships?

That cargo ship pollution stat refers to NOx, SOx, and other particulate pollutants—cars are now incredibly clean when it comes to that so even using a leaf blower without modern pollution controls has more air pollution than a gasoline truck driving cross-country. CO2 on the other hand is still emitted in large amounts from cars, and ships do not emit as much in comparison. Ships should be forced to use scrubbers but that would fix smog rather than climate change.

1) Twin Oaks, an intentional community near Charlottesville, VA has been around for 50 years and take extremely detailed records, which are being researched by a university. (Can't remember which one tho...maybe Alabama)

They have about 100 adults and 15 kids, they share buildings and resources and grow much of their food. Their diet, depending on the current residents, tends to lean towards mostly plant based. Their carbon footprint is 80% less than if they were living separately, their happy index is far higher, and they only need to earn about $6,000 per person per year to make it financially viable. The kicker? By most measures, they live extremely comfortable, upper middle class lifestyles and have far more leisure time than the average u.s. citizen.

Has any of your research considered intentional communities?

2) I live in a tiny house on wheels and as a result, my daily electrical consumption is about 2kWh. Also, a nice side effect of living tiny is there is limited space to store junk, so a minimalist consumer lifestyle becomes necessary (and is extremely liberating!)

Have you done any research on the amount of reduction arising from families switching to tiny houses?

(Side note: I grow a sizable chunk of my own food. I eat a plant based diet. I compost my waste. I live in a mini village setting (not Twin Oaks) and share some resources. And I only work about 10-15 hours a week now because my cost of living was decreased by 65ish%. I highly recommend the tiny house route!)

I've noticed there's a disparity between how much energy something consumes (and therefore, all else being equal, how much greenhouse gas it emits) and how much it feels like it consumes. E.g. There are campaigns advocating turning off standby LEDs, which consume hundreds to tenths of a watt. By contrast, just about anything that creates heat takes several kilowatts, literally tens to hundreds of thousands of times as much energy. Conversely, novel green energy methods (like tiles that generate energy waking on them) receive uncritical news coverage with no comparison to conventional methods. How do you think the dialogue and behaviour can be shifted towards pragmatic measures rather feel-good ones?

Secondly, what role do you think non-personal, e.g. government and corporate decisions have to play? Businesses seem to like to shift environmental responsibility to the consumer.

There's a great study by Attari et al. showing that people make "small overestimates for low-energy activities (like light bulbs) and large underestimates
for high-energy activities (like clothes dryers and air conditioners)."

What technology do you think has the biggest chance of making an impact in the future?

I've heard that it is very important for countries that are now developing to do so in a way that is more renewable - how true do you think this is?

Also, do you think it is fair to make developing countries, many of which are just starting to develop their energy grids, etc, develop with renewable energy rather than non renewable energy, like developed countries have?

Yes, you are absolutely right in thinking that a car generates a lot of pollution just by being produced. That's why our analysis includes the embodied emissions of a car. There is therefore going to be a payback time where you will have to drive the newer more efficient car for a certain period before it becomes worthwhile.

One study found that car owners who participated in a Japanese car scrapping program (trading in old cars for more efficient cars) would need to own the new cars for 4.7 years to make the switch pay off. But switching to an even more efficient vehicle, like a hybrid, can shorten this time. Answering your specific question would therefore depend on how long you owned the first vehicle. But if your vehicle is dying and you definitely need a new car, then buying the most efficient car possible is a safe choice.

As for your law firm, it's likely that the emissions from flying outweigh the emissions from paper usage - by a lot. I work at a university and, of course, we also use a lot of paper, but emissions from air travel are about 27x greater than from paper usage, and my recent research suggests that this is a conservative estimate.

Convincing your firm to invest in high quality video conferencing equipment could easily pay off both from a cost and environmental standpoint. I don't know where you're located but depending on the region you might also be able to take high speed rail that saves you time compared to flying and also reduces emissions. Lastly, a law firm might also have the resources to pay for a carbon audit and get personalized answers to these questions.

it is really refreshing to finally see climate change and plant-based diets in the same conversation. anecdotally, most climate change conversations completely gloss over the damage of factory farming on the planet. so thank you for that.

does your calculation of CO2 emission of an omnivorous diet include the upstream consequences of factory farming, including deforestation and water consumption? or is it only based in direct emissions from factories themselves?

Water consumption shouldn't really be generating emissions directly, so that would fall outside the boundaries of our calculations. Studies definitely do examine water usage by different forms of agriculture though.

The studies that contributed to our final calculations include emissions from fertilizers, methane production by livestock and transport of food to retail centers. Emissions from land use change (like deforestation) are harder to quantify. Some research has answered the question about how much emissions are created by deforesting an area and using it to raise cattle or farm shrimp and the effects can be quite large.

What are some outdoor practices that could help, which are often overlooked? I know alone I can't make a difference, but that's not a sufficient reason to not do something right, because billions doing it can make a difference.

Yes. The carbon produced from a typical carnivorous diet comes from the emissions of growing, harvesting, and shipping meat, as well as methane produced by the animals themselves.

I don’t believe there is any significant difference between any carbon emissions you produce when eating a plant based vs. meat diet, but in any case, I think it would be much less significant than the reduction from no longer relying on the factory farm production of meat.

The more food (plant, meat, whatever) you can get locally or harvest yourself, the better!

In a “business as usual” world with continued high greenhouse gas emissions and an energy system reliant on fossil fuels, we are headed for +4°C or more of warming, and we are in very big trouble indeed.

In a world where we succeed in making the changes necessary to stay well below 2°C, there will still be some impacts and losses from climate change, but it is much more feasible to imagine everyone on Earth having the possibility for a good life.

A +4°C world seriously threatens our continued ability to produce sufficient food, maintain healthy ecosystems, and enable sustainable development… pretty fundamental things to a good life on planet Earth. (Supporting these three goals are the objectives of the UN Framework Convention on Climate Change, which was adopted in 1992, and is the basis of the international negotiations that led to the Paris Agreement.)

One note regarding the scale labels: I think the decision whether or not to have a child is an extremely personal one, so I would never judge for someone else whether there is a “point” to having a child. For people who yearn for a child, and who know the science, recognize how serious the risk of climate change is, and how urgent it is that we reduce emissions, I think that having a child is a vote of hope that we can actually tackle the climate challenge, and I think it’s a big responsibility for parents to do everything possible in their own life, in the lifestyle in which they raise their child, and in their sphere of influence to ensure that child (and everyone else on Earth) lives in a safe climate.

People that doubt the effectiveness of forest offsets worry about their longterm viability. The carbon that is being stored in carbon offsets is vulnerable to being released in the atmosphere again until it buried in the earth beneath the forest floor.

I have a question regarding flying vs. driving. My husband and I live in Toronto; the rest of my family lives near Boston. We fly down to see them three times a year on average, always flying coach with only hand luggage. Unfortunately there is no viable train option between the two cities (the only possibility involves 21 hours of travel and a possible overnight stay in New York).

We don't currently own a car, and we like it that way as we can easily rely on public transit in Toronto. However, we have sometimes talked about getting one and driving, rather than flying, when we travel to Boston. It's about a 9-10 hour drive. If we did buy a car, we would at the very least buy an electric hybrid (my husband likes the Chevy Volt). Financially, the cost of the three flights more or less works out to our estimated annual car expenses, so it's more a question of environmental impact. We always say that we would continue to take mainly transit here in the city; however, I'm sure that if we had the car, it would be tempting to use it more than we plan right now out of convenience.

The question is, what's worse: living car-free but having to take at least three flights a year, or getting a car but using it very rarely for longer trips? If flying is the least worst option, is there anything more we can do to mitigate the impact, such as purchasing offsets? If we did get a car, do you have a recommendation about the best budget model for a two-person family? We don't have kids so we don't need a big vehicle to haul stuff. Thanks very much for your thoughts on this!

Not really answering your question but if possible with work schedule, try to take one long visit to family rather than several short ones. I now only fly once per year and try to include business, family, and vacationing in the trip.

The findings show that many of the most commonly adopted strategies are far less effective than the ones we don't ordinarily hear about. Namely, having one fewer child, which would result in an average of 58.6 metric tons of CO2-equivalent (tCO2e) emission reductions for developed countries per year. The next most effective items on the list are living car-free (2.4 tCO2e per year), avoiding air travel (1.6 tCO2e per year) and eating a plant-based diet (0.8 tCO2e per year

You consider climate change as an individual objective. I would like to point out that climate preservation is not the only objective. We also have quality of life, social security etc. as objectives we would like to achieve. For example, we know that some countries in Europe and Japan face an impending catastrophic demographic problem. So, the 1 less child might help the environment but it pretty much turns over human beings which is one of the main reasons why we talk about climate change.

One child less sounds great for so many reasons. Plant based or at least minimal meat diet totally makes sense. What are some solutions to americans especially, where 2/3 of the population do NOT live in compact urban areas, and even some of those that do, don't have realistic access to public transportation to live car free?

Also, in the grand scheme of things, do you have any numbers on how much impact large companies, say fortune500 companies, can make on co2 emissions compared to average working class individuals?

It's never sat right with me that these huge companies that cut corners to save pennies and have unethical practices that harm people, the planet, etc, try to tell ME to please limit to 1 paper towel when washing my hands in the bathroom.

Recently saw a documentary regarding choices we as consumers make that help the planet, and avoid or mitigate climate change. Are there any businesses you folks recommend that people support or check out because of their climate consciousness?

I am a bioinformatician using machine learning and statistics to study microorganisms in the environment and in people. I want to help out with the efforts of climate change on my spare time. Are there any competitions like kaggle or the dream competition that are specific for climate change related topics? How can I help with my skill set besides donating and being conscious about my impact on the environment? Is there a place where people post the datasets and a specific research question for the public to build predictive models or classifiers?

Cool, this is so great! I'm not aware of posted datasets for open source answering (great idea!) but there are hackathons like Open Hack or Climathon. You could always contact a researcher at your local university, or start going to seminars or public lectures to find a scientist in your area, if you wanted to establish a local collaboration.

Unfortunately we are not experts on the effects of climate change on health. What we can tell you is that some of the most important actions you can take as an individual for the benefit of the climate are also really good for your health!

Hi I'm from India. The pollution in some of our cities(Delhi, Mumbai etc.) are going way beyond extreme levels. What's the optimal solution to this dangerous problem. (Keep in mind that in a big and diverse country like ours, policies can change after every elections)
Thanks.

I never see the inevitable switch to eating plants discussed in the mainstream media. When you take into account the clearing of rainforests for arable land on which to grow feed for livestock, the unparalleled CO2 emissions of animal agriculture, the toxic runoff from farms, the inordinate consumption of water, and the massive use of pesticides, growth hormones, antibiotics, etc. that are vital to the production of so much meat and other animal products, why is it that eliminating meat from people's diets isn't higher on the agenda for climate scientists worldwide?

"Namely, having one fewer child, which would result in an average of 58.6 metric tons of CO2-equivalent (tCO2e) emission reductions for developed countries per year. The next most effective items on the list are living car-free (2.4 tCO2e per year), avoiding air travel (1.6 tCO2e per year) and eating a plant-based diet (0.8 tCO2e per year)."

So I should have one less child, stop eating meat, take trains(?) for my business trip and of course take a bike or a bus to work everyday (here in winter it gets as cold as -15~20C) while all the car dealerships, mall, some office buildings all over the country keep their lights on every night? (without talking about cruise ship and other big polluter)

I know every little counts, but I doubt the savings through my action or of the thousands of people (by restricting ourselves) would even dent the impact the big guys have on climate change.

Hi,
I am an undergrad in my sophomore year taking a class on "Climate Change and Risk Communication," with a focus on "Serious Games" being used to convey climate change information. My question is, have any of you researched Climate Change Games, and if so, what is your opinion on their effectiveness?

My colleague Joost Vervoort has developed "game jams" to get people involved in envisioning a good Anthropocene, and these have been really creative and inspiring. You might reach out to him to see if he can comment on research on their effectiveness.

I eat a plant based diet, due to environmental reasons mostly but also nice for the animals, however if I eat pre packaged meat substitutes like say Gardein products how bad is the environmental impact from eating a meat substitute that is mass produced? I'm thinking they need ingredients shipped to them to produce the product and then it's commercially packaged in plastic freezer bags and shipped to me. Is it just as bad as if I ate meat?

No, you are still removing an entire trophic level by consuming plants rather than meat (i.e. far, far less plants and therefore land clearing, manufacturing of feed, transport of feed and animals etc), although the manufacturing and shipping of these faux meat products still obviously has an impact... just less than if you were consuming meat.

I know, it can't really be classified as a lifestyle choice, but... considering the impact of having one child less is on top of that list, is it possible to estimate an impact of suicide? Would it be more or less than having one child less?

I am very conscious of my carbon footprint, but find that many of my friends do not seem to care. I have tried explaining to them the importance of "going green" but it goes nowhere. What would you recommend to encourage people to be more conscious of their individual habits and choices?

Sometimes people aren't going to be swayed by caring for the planet. But a lot of the choices that we recommend are also good for your health and your wallet.

As I noted here, eating a plant-based diet reduces your chances of getting Type II diabetes and some forms of cancer. And living without a car also has health benefits for yourself and others around you. These are good choices to make regardless of the climate!

I have a mitochondrial disease that requires I eat red meat plus take supplements found in red meat. I also have PCOS which makes me very susceptible to anaemia. I aim to eat about 100gms of red meat 5 times a week, or 0.5 a kilogram per week. I believe this is lower than average for US meat eaters. How much Carbon am I putting into the air each year from this. Is it actually lower than average?

If you don't want to that's fine, I understand it's personal, but I am interested in this mitochondrial disease for which you have to eat red meat, I haven't heard of that before. Do you have a more specific name that I might be able to look up and do some research? and or some links that specifically show that someone with your condition must eat red meat to be healthy.

Where might one get started as far as doing independent research through the literature on climate change? I understand the greenhouse effect and such but could I find reliably sourced information that models/predicts the effects this will have on climate and by extension ecosystems, in a way that's accessible to someone who isn't a professional climate scientist?

Hi Nick, the most comprehensive starting point would be the Summaries for Policymakers from the IPCC. Skeptical Science is a good starting point for accessible summaries with links to peer-reviewed literature.

Hello everyone! Many thanks for doing this. I have a few questions for you related to how we can enact what we have learned in academia and apply it to the real world.

I have an MSc in Geography from University College London and I am currently back in my home country.

It has been one year already and I am still struggling to find a job related to my area of expertise - which is about human social behaviour and sustainability; in other words, I study the reasons behind people's habits and how they relate to sustainability.

It just feels like not many people and companies are concerned about this topic in my country: climate change is not a big political issue and most citizens don't even know the dangers behind it and what needs to be changed in order to mitigate it.

This is one of the reasons why I actually decided to come back and not pursue a PhD at UCL. I wanted to help my country with what I have learned during my studies.

However, I can't find a job related to this issue and I just feel very frustrated because I feel I'm doing nothing! This has led me to reconsider and think about other options for my career. I might go back to studying a PhD or just emigrate to another country altogether.

But I don't wanna give up just yet. I really want to help. People with my education are desperately needed in my country. Scientists and people with academic backgrounds are the ones that need to be taking decisions regarding environmental politics and policy.

So, these are my questions:

What are some strategies scientists use to communicate knowledge to the public?

What are some strategies scientists use to foster climate change mitigation in THEIR communities?

Can an academic become a politician or a decision maker? If this is so, do you have any examples of climate and environmental scientists that have been able to impact their government's agenda (I'd like to follow their examples)?

To answer part of your question on what strategies scientists use to communicate knowledge to the public, there is a lot of research about what works and what doesn't and some of it is contested. This handbook is an interesting place to start.

As for effective climate change communicators, Katharine Hayhoe is one climate scientist who I admire. Maybe have a look at her website as a starting place.

In terms of local transportation emissions and building emissions evidence suggests that denser areas have lower emissions. The logic being that when you fit more people in less space the buildings take less energy to heat, the neighbourhoods are more walkable, and when you do need to drive it's not as far to get from where you live to where you need to go.

When considering dietary choices, is there any measurable benefit of eating locally sourced animal products? For example, am I reducing my emissions by eating beef from a cow my neighbor slaughtered on his small organic farm rather than buying beef in the store?

Thank you for the opportunity! In recent years I've become interested in sustainable (and ethical) choices in fashion, I know mainstream media has attempted to answer this but can't seem to do so without sensationalism,

I know you are focusing more on the specifics your have listed above but in comparison what is the impact of the fashion world on the environment?

Is there a significant difference between companies providing options and retaining some of their fast fashion practices vs those not providing sustainable options?

Are there concrete ways to identify when marketing makes exaggerated claims to products that are barely an improvement? Are there companies to actively avoid or is that a moot point?

Are there ways to keep up with ongoing developments in sustainability in durable goods and consumables?

The majority of the discussion about CO2 discussion seems to be centered around meat consumption/production and comparing that to vegetable production/consumption. I am curious how does fish and seafood compare to this, purely from a CO2 perspective, disregarding other environmental issues mass-fishing causes.

I've heard of scientists trying to grow meat in labs rather than harvesting live animals. I assume, if this were to go into consumer production, this would also have a huge impact of the reduction of CO2. Would it be equivalent to switching to a plant-based diet?

Hi! Dont know if you're still answering questions but, for some time now I have been trying to advocate and experiment more in bug foods.

I was curious if you've ever looked into the impact bug farming would make on the world? Based on your earlier reply it would most definitely better than beef, but would this be a better alternative to even say fish and other small game?

I am late to the party but I have a tangential question; I'm an ICU-nurse and I feel like I'm wrecking the environment locally and globally with all the different drugs/chemicals and single-use items plus packaging I use every single day.

Is there any data on the contribution to climate change from the health care sector and how do I reduce it without compromising patient safety?

"“People want to reduce environmental emissions, but they will start where it hurts least,” he says, adding that the biggest impact will come from many people taking small steps rather than a few people making drastic lifestyle changes."

Your research shows the CO2 impact reduction IF families start having less children. However, what's the practical reality of this? When trying to find ways to live more sustainably, is there even a more dehumanizing choice than choosing to have fewer humans? Does your research make any attempt to quantify the reality of people following your suggestions?

Aren't you far more likely to convince someone in a coal powered region to install solar panels, rather than not to have that 2nd child?

On an individual level you may convince a small number of people to drastically alter their family plans. But won't those efficiency gains be a drop in the bucket when compared to massive adoption of more realistic lifestyle changes? Like recycling, electric cars, and solar panels.

EDIT:

Nobody will ever see this as it's been buried, but I need to ask where your value of 58.6 t CO2 / yr comes from.

AFAICT you've simply used the constant factor approach from the Murtaugh, Schlax paper without making any mention of the pessimistic, optimistic, and constant rate calculations that your primary source used. Unfortunately, it looks like you've simply cherrypicked a convenient number to tell a better story

AFAICT 58.6, when multiplied out by 80 (the length of life used in the reference paper) gives 4688 t of lifetime CO2 emissions. A value somewhere between the "constant" and "optimistic" levels given in table 3 from the Murtaugh, Schlax paper. In fact your paper never mentions how future CO2 levels are discounted, not does it mention the methods by which you arrived at 58.6. Or did I miss it?

Also Murtaugh, Schlax make it very apparent in their paper that the estimates are heavily skewed for US households:

"The range of values is enormous: under the
constant-emission scenario, the legacy of a United States female
(18,500 t) is two orders of magnitude greater that of a female from
Bangladesh (136 t)."

Your paper makes only a brief notion towards this with a small table in figure 1 showing 120 t/yr savings for the US. Which is close to the 9441 tCO2 / 80 years in the Murtaugh, Schlax paper for the constant scenario calculation.

At best your approach and estimates appear flawed. At worst, it appears to be politics masquerading as science.

"Going car free" might be a lot better, but theresany reasons why that isn't always possible, but "using your car less" is definitely possible and is even self serving, less personal car use will encourage governments to actually create and manage effective public transport and keep cities and towns navigable without cars.

As an example, one of the cities near me is so bad that even driving a car in it is a bad option, but except for a small minority of the city's the public transport is terrible too. (Somehow that part of the city with decent PT is also the part with the best traffic, so kinda sellf defeating) but the universities there decided to work together to set up better transport systems for their students, which they did by working with the PT companies, which led to far better PT and now the whole section of the city is evolving into a much better area where people actually can live without cars.

You're correct that it's definitely not possible for everyone to get by without a car. So yes, it's not just up to individuals to take these climate-saving actions on. Ex. better city planning can make it easier for people to get around on foot or by public transit.

I consider myself as someone who tries to live consciously, though I do have my faults. With that being said, I believe that big industry and lack of proper legislation contributes to our carbon footprint more than the average individual. Short of active boycotting/legislation reform/etc., how much of an impact would an individual choosing to shop local, small businesses have on carbon emissions? E.g. Shopping at numerous local mom & pop's vs. going to Walmart.